The present invention relates towards a mirror angle adjustment structure provided for introducing a light beam to an object in an optical system for a laser beam scanning unit, electronic copying machine and the like.
Conventionally, in the optical system for a laser beam printing device, electronic copying machine and the like the outside periphery of a photoconductive drum, the outside peripheral surface of which is formed of a photoconductive material, is scanned with a laser beam modified based on image and character information, and the information is printed on a recording paper by making use of an electrophotographic method. A light beam is introduced to a desired portion in such a manner that a light beam path is bent after the light beam is reflected from a mirror. This arrangement increases the freedom of positioning disposition of a light source and optical elements to thereby enable the device to be made compact as a whole and the length of a light path necessary for achieving an optical performance to be obtained.
The mirror is mounted on the chassis of the device, the unit base for an optical system unit or the like at a predetermined angle for reflecting an incident light beam in a desired direction, and a mechanism for adjusting the angle of the mirror is disposed on the portion where the mirror is disposed so that the direction in which the light beam is reflected can be finely adjusted.
The mirror angle adjustment mechanism is arranged such that, for example, a support projection is projected from a mirror support member such as the chassis, unit base or the like at a position corresponding to an end, along the lengthwise direction of the mirror. An adjustment screw disposed at the other end of the mirror corresponding to the above end across the mirror is passed through and threadedly engaged with the mirror support member from the backside thereof. The extreme end of the adjustment screw is projected to tile mirror side. Further, an urging means such as a leaf spring or the like is provided for pressing the mirror to the support projection and adjustment screw. The mirror is fixed by being pressed against the support projection and adjustment screw by the urging means, and when the adjustment screw is turned from the backside of the mirror support member in an advancing or retracting direction, an angle of the mirror can be adjusted in such a manner that the mirror is swung about the support projection serving as a fulcrum.
Nevertheless, with the aforesaid mirror angle adjustment structure, the angle must be adjusted by turning the adjustment screw from tile backside of the mirror mounting surface and thus this adjustment operation is very time consuming.